1. Field of the Invention
The present invention relates to a power steering, and particularly to an electronic control power steering including a control unit for electronic control, and more particularly to an electronic control power steering having different power-assist for steering according to a tilt angle of a steering column.
2. Description of the Related Art
A power steering is broadly used as a system capable of providing power assist for steering to the driver so as to be able to turn a vehicle with a weak hand-operated force of a steering wheel. Here, there are two modes according to a power source, one for a hydraulic pump mode and the other for an electric motor mode. In particular, the power steering controlled electronically and automatically is called an electronic control power steering.
As the conventional electronic control power steering, one example of the electric motor mode is disclosed in U.S. Pat. No. 5,810,111, and one example of the hydraulic pump mode is disclosed in U.S. Pat. No. 6,499,557.
The control unit included in the conventional electronic control power steering has logic capable of sensing a vehicular speed from a signal of a vehicular speed sensor and then controlling power assist for steering according to the sensed result. Thus, the control unit is generally a speed sensitive typed one providing the power assist for steering at a low speed. The conventional power steering is simply capable of controlling the power assist for steering according to the speed in this manner, but not controlling the power assist for steering according to a condition of driver's body.
Meanwhile, the steering column is generally provided with a tilt system so that the driver can adjust a location of the steering wheel according to a condition of his/her own body. One example of the tilt system is disclosed in U.S. Pat. No. 6,637,284.